Basso Mouse Scale for locomotion detects differences in recovery after spinal cord injury in five common mouse strains

Genetically engineered mice are used extensively to examine molecular responses to spinal cord injury (SCI). Inherent strain differences may confound behavioral outcomes; therefore, behavioral characterization of several strains after SCI is warranted. The Basso, Beattie, Bresnahan Locomotor Rating Scale (BBB) for rats has been widely used for SCI mice, but may not accurately reflect their unique recovery pattern. This study's purpose was to develop a valid locomotor rating scale for mice and to identify strain differences in locomotor recovery after SCI. We examined C57BL/6, C57BL/10, B10.PL, BALB/c, and C57BL/6x129S6 F1 strains for 42 days after mild, moderate, and severe contusive SCI or transection of the mid thoracic spinal cord. Contusions were created using the Ohio State University electromagnetic SCI device which is a displacement-driven model, and the Infinite Horizon device, which is a force-driven model. Attributes and rankings for the Basso Mouse Scale for Locomotion (BMS) were determined from frequency analyses of seven locomotor categories. Mouse recovery differed from rats for coordination, paw position and trunk instability. Disagreement occurred across six expert raters using BBB (p < 0.05) but not BMS to assess the same mice. BMS detected significant differences in locomotor outcomes between severe contusion and transection (p < 0.05) and SCI severity gradations resulting from displacement variations of only 0.1 mm (p < 0.05). BMS demonstrated significant face, predictive and concurrent validity. Novice BMS raters with training scored within 0.5 points of experts and demonstrated high reliability (0.92-0.99). The BMS is a sensitive, valid and reliable locomotor measure in SCI mice. BMS revealed significantly higher recovery in C57BL/10, B10.PL and F1 than the C57BL/6 and BALB/c strains after moderate SCI (p < 0.05). The differing behavioral response to SCI suggests inherent genetic factors significantly impact locomotor recovery and must be considered in studies with inbred or genetically engineered mouse strains.

Occurrence, metabolism, metabolic role, and industrial uses of bacterial polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs), of which polyhydroxybutyrate (PHB) is the most abundant, are bacterial carbon and energy reserve materials of widespread occurrence. They are composed of 3-hydroxyacid monomer units and exist as a small number of cytoplasmic granules per cell. The properties of the C4 homopolymer PHB as a biodegradable thermoplastic first attracted industrial attention more than 20 years ago. Copolymers of C4 (3-hydroxybutyrate [3HB]) and C5 (3-hydroxyvalerate [3HV]) monomer units have modified physical properties; e.g., the plastic is less brittle than PHB, whereas PHAs containing C8 to C12 monomers behave as elastomers. This family of materials is the centre of considerable commercial interest, and 3HB-co-3HV copolymers have been marketed by ICI plc as Biopol. The known polymers exist as 2(1) helices with the fiber repeat decreasing from 0.596 nm for PHB to about 0.45 nm for C8 to C10 polymers. Novel copolymers with a backbone of 3HB and 4HB have been obtained. The native granules contain noncrystalline polymer, and water may possibly act as a plasticizer. Although the biosynthesis and regulation of PHB are generally well understood, the corresponding information for the synthesis of long-side-chain PHAs from alkanes, alcohols, and organic acids is still incomplete. The precise mechanisms of action of the polymerizing and depolymerizing enzymes also remain to be established. The structural genes for the three key enzymes of PHB synthesis from acetyl coenzyme A in Alcaligenes eutrophus have been cloned, sequenced, and expressed in Escherichia coli. Polymer molecular weights appear to be species specific. The factors influencing the commercial choice of organism, substrate, and isolation process are discussed. The physiological functions of PHB as a reserve material and in symbiotic nitrogen fixation and its presence in bacterial plasma membranes and putative role in transformability and calcium signaling are also considered.

Human neural stem cells differentiate and promote locomotor recovery in spinal cord-injured mice

We report that prospectively isolated, human CNS stem cells grown as neurospheres (hCNS-SCns) survive, migrate, and express differentiation markers for neurons and oligodendrocytes after long-term engraftment in spinal cord-injured NOD-scid mice. hCNS-SCns engraftment was associated with locomotor recovery, an observation that was abolished by selective ablation of engrafted cells by diphtheria toxin. Remyelination by hCNS-SCns was found in both the spinal cord injury NOD-scid model and myelin-deficient shiverer mice. Moreover, electron microscopic evidence consistent with synapse formation between hCNS-SCns and mouse host neurons was observed. Glial fibrillary acidic protein-positive astrocytic differentiation was rare, and hCNS-SCns did not appear to contribute to the scar. These data suggest that hCNS-SCns may possess therapeutic potential for CNS injury and disease.

Quantitative analysis of cellular inflammation after traumatic spinal cord injury: evidence for a multiphasic inflammatory response in the acute to chronic environment

Traumatic injury to the central nervous system results in the disruption of the blood brain/spinal barrier, followed by the invasion of cells and other components of the immune system that can aggravate injury and affect subsequent repair and regeneration. Although studies of chronic neuroinflammation in the injured spinal cord of animals are clinically relevant to most patients living with traumatic injury to the brain or spinal cord, very little is known about chronic neuroinflammation, though several studies have tested the role of neuroinflammation in the acute period after injury. The present study characterizes a novel cell preparation method that assesses, quickly and effectively, the changes in the principal immune cell types by flow cytometry in the injured spinal cord, daily for the first 10 days and periodically up to 180 days after spinal cord injury. These data quantitatively demonstrate a novel time-dependent multiphasic response of cellular inflammation in the spinal cord after spinal cord injury and are verified by quantitative stereology of immunolabelled spinal cord sections at selected time points. The early phase of cellular inflammation is comprised principally of neutrophils (peaking 1 day post-injury), macrophages/microglia (peaking 7 days post-injury) and T cells (peaking 9 days post-injury). The late phase of cellular inflammation was detected after 14 days post-injury, peaked after 60 days post-injury and remained detectable throughout 180 days post-injury for all three cell types. Furthermore, the late phase of cellular inflammation (14-180 days post-injury) did not coincide with either further improvements, or new decrements, in open-field locomotor function after spinal cord injury. However, blockade of chemoattractant C5a-mediated inflammation after 14 days post-injury reduced locomotor recovery and myelination in the injured spinal cord, suggesting that the late inflammatory response serves a reparative function. Together, these data provide new insight into cellular inflammation of spinal cord injury and identify a surprising and extended multiphasic response of cellular inflammation. Understanding the role of this multiphasic response in the pathophysiology of spinal cord injury could be critical for the design and implementation of rational therapeutic treatment strategies, including both cell-based and pharmacological interventions.

Immunohistochemical evidence for apoptosis in Alzheimer's disease

Recently, in vitro studies conducted in our laboratory and others have suggested that apoptosis may have a role in the neuronal cell death associated with Alzheimer's disease (AD). To evaluate this hypothesis, the hippocampi and entorhinal cortices of AD, aged control, and surgical biopsy tissue were examined using the ApopTag system for the detection of DNA fragmentation and DNA strains to reveal nuclear morphology. Numerous neuronal nuclei displaying distinct morphological characteristics of apoptosis were present within tangle-bearing neurons as well as non-tangle-bearing neurons in AD brain, whereas few or no such nuclei were detected in control brain. Our in vivo results support the hypothesis that apoptosis may be one mechanism leading neuronal cell death in AD.

A potential role for apoptosis in neurodegeneration and Alzheimer's disease

Previous studies have shown that beta-amyloid (A beta) peptides are neurotoxic. Recent data suggest that neurons undergoing A beta-induced cell death exhibit characteristics that correspond to the classical features of apoptosis, suggesting that these cells may initiate a program of cell death. This chapter explores the criteria and precautions that must be applied to evaluate mechanisms of cell death in vitro and in vivo, discusses the evidence supporting an apoptotic mechanism of cell death in response to A beta in cultured neurons, and describes potential correlations for these findings in the Alzheimer's disease brain. In addition, cellular signaling pathways that may be associated with apoptosis in response to A beta are examined, and support for apoptosis as a mechanism of cell death for other neurodegeneration-inducing stimuli (e.g., oxidative injury) is described. The connection of multiple stimuli that induce neuronal cell death to an apoptotic mechanism suggests that apoptosis could play a central role in neurodegeneration in the brain.

Postmenopausal use of estrogen and occlusion of coronary arteries

The degree of coronary artery occlusion was compared between users and nonusers of postmenopausal estrogen among 933 female patients undergoing angiography between the ages 50 and 75 years in the Milwaukee Cardiovascular Data Registry. Users (n = 154) had less occlusion than nonusers (n = 779), and a significant increase in occlusion scores with age was evident for nonusers (p less than 0.001) but not for users (p = 0.50). The age-adjusted odds ratios for use of postmenopausal estrogen among women with moderate and severe levels of occlusion of the coronary arteries were 0.59 (95% confidence interval, 0.48 to 0.73) and 0.37 (95% confidence interval, 0.29 to 0.46), respectively, which indicated a statistically significant, apparent protective effect of postmenopausal estrogen on coronary occlusion. This effect was independent of the type of menopause or other risk factors but not independent of high-density lipoprotein-cholesterol levels. Higher high-density lipoprotein-cholesterol levels among users may indicate a biologic mechanism by which postmenopausal estrogen use lowers the risk of coronary occlusion.

Relation of lipoprotein subclasses as measured by proton nuclear magnetic resonance spectroscopy to coronary artery disease

Although each of the major lipoprotein fractions is composed of various subclasses that may differ in atherogenicity, the importance of this heterogeneity has been difficult to ascertain owing to the labor-intensive nature of subclass measurement methods. We have recently developed a procedure, using proton nuclear magnetic resonance (NMR) spectroscopy, to simultaneously quantify levels of subclasses of very low density (VLDL), low density (LDL), and high density (HDL) lipoproteins; subclass distributions determined with this method agree well with those derived by gradient gel electrophoresis. The objective of the current study of 158 men was to examine whether NMR-derived lipoprotein subclass levels improve the prediction of arteriographically documented coronary artery disease (CAD) when levels of lipids and lipoproteins are known. We found that a global measure of CAD severity was positively associated with levels of large VLDL and small HDL particles and inversely associated with intermediate size HDL particles; these associations were independent of age and standard lipid measurements. At comparable lipid and lipoprotein levels, for example, men with relatively high (higher than the median) levels of either small HDL or large VLDL particles were three to four times more likely to have extensive CAD than were the other men; the 27 men with high levels of both large VLDL and small HDL were 15 times more likely to have extensive CAD than were men with low levels. In contrast, adjustment for levels of triglycerides or HDL cholesterol greatly reduced the relation of small LDL particles to CAD. These findings suggest that large VLDL and small HDL particles may play important roles in the development of occlusive disease and that their measurement, which is not possible with routine lipid testing, may lead to more accurate risk assessment.

Characterization of a potassium channel toxin from the Caribbean Sea anemone Stichodactyla helianthus

A peptide toxin, ShK, that blocks voltage-dependent potassium channels was isolated from the whole body extract of the Caribbean sea anemone Stichodactyla helianthus. It competes with dendrotoxin I and alpha-dendrotoxin for binding to synaptosomal membranes of rat brain, facilities acetylcholine release at an avian neuromuscular junction and suppresses K+ currents in rat dorsal root ganglion neurones in culture. Its amino acid sequence is R1SCIDTIPKS10RCTAFQCKHS20MKYRLSFCRK30TCGTC35. There is no homology with other K+ channel-blocking peptides, except for BgK from the sea anemone Bunodosoma granulifera. ShK and BgK appear to be in a different structural class from other toxins affecting K+ channels.

Odor-induced increases in c-fos mRNA expression reveal an anatomical "unit" for odor processing in olfactory bulb

Expression of the immediate-early gene c-fos was used to evaluate the coordinate activation of olfactory bulb neurons by brief exposure to specific odors in the alert rat. In situ hybridization to c-fos mRNA was compared to regional increases in 2-deoxy-D-[14C]glucose incorporation in an adjacent section analysis. Levels of c-fos mRNA in olfactory bulb were high in rats recently removed from their home cage but were low in animals placed in a relatively odor-free chamber for 30 min. Presentation of specific odors to alert rats for as little as 5 min increased c-fos mRNA in radially distributed neuronal ensembles that spanned the lamina of the main olfactory bulb. The complementary RNA (cRNA)-labeled neuronal collectives consisted of cells in the glomerular layer that precisely defined the borders of individual glomeruli and underlying tufted, mitral, and granule cells. The activated fields were much broader in the granule cell layer than in the overlying glomerular layer and thus exhibited a flask-like, as opposed to a columnar, contour. The bulbar distribution of cRNA-labeled cell arrays differed with different odors and, in the glomerular layer, corresponded to focal regions of high 2-deoxy-D-[14C]glucose uptake. Administration of the noncompetitive N-methyl-D-aspartate receptor antagonist MK801 did not attenuate the odor induction of c-fos but, instead, increased c-fos mRNA levels throughout the bulb. We propose that the neuronal ensembles expressing increased c-fos mRNA with odor stimulation represent principal functional units of sensory processing in the main olfactory bulb of the behaving rat.

Activated caspase-3 expression in Alzheimer's and aged control brain: correlation with Alzheimer pathology

Several studies have suggested that activated caspase-3 has properties of a cell death executioner protease. In this study, we examined the expression of activated caspase-3 in AD and aged control brains. Activated caspase-3 immunoreactivity was seen in neurons, astrocytes, and blood vessels, was elevated in AD, and exhibited a high degree of colocalization with neurofibrillary tangles and senile plaques. These data suggest that activated caspase-3 may be a factor in functional decline and may have an important role in neuronal cell death and plaque formation in AD brain.

Chemotherapy alone or chemotherapy with chest radiation therapy in limited stage small cell lung cancer. A prospective, randomized trial

STUDY OBJECTIVE

To determine the effect of concurrent chest radiation therapy on response rate, recurrence, and treatment toxicity among patients with limited stage small cell lung cancer who are receiving combination chemotherapy.

DESIGN

Randomized trial with a median follow-up of 57 months.

SETTING

A single government institution--the National Cancer Institute.

PATIENTS

Consecutive sample of 96 patients with histologically confirmed small cell lung cancer that was confined to the hemithorax of origin or mediastinal and supraclavicular nodes, and which could be encompassed within a tolerable radiation portal ("limited stage"). All patients were followed until death or the end of the study period.

INTERVENTIONS

Chemotherapy: Cyclophosphamide, methotrexate, and lomustine in 6-week cycles alternating with vincristine, adriamycin, and procarbazine in 6-week cycles, for a total of 48 weeks. Radiation therapy: Chest irradiation to 40 Gy in 15 fractions over 3 weeks, given simultaneously with the first chemotherapy cycle.

MEASUREMENTS AND MAIN RESULTS

The combined therapy led to a significantly higher response rate (complete responses, 81%, compared with partial responses, 43%; 95% Cl for the difference, 20% to 56%), significantly improved local control of the chest tumor (p less than 0.001), and significantly longer survival (p less than 0.035) (median, 15.0 months, compared with 11.6 for chemotherapy alone). The combined therapy produced significantly more myelosuppression, weight loss, esophagitis, and pulmonary dysfunction. There were more infections and deaths from toxicity in the combined treatment group, but the differences between groups were not statistically significant.

CONCLUSION

A regimen of combined chemotherapy and chest radiation therapy given concurrently is superior to chemotherapy given alone in inducing remission and prolonging survival in patients with limited stage small cell lung cancer, and the benefit of combined therapy is reduced by its greater toxicity.

Proteins from plant cell walls inhibit polygalacturonases secreted by plant pathogens

Proteins extracted from the cell walls of Red Kidney bean hypocotyls, tomato stems, and suspension-cultured sycamore cells can completely inhibit the activity of the polygalacturonases (polygalacturonide hydrolases, EC 3.2.1.15) secreted by the fungal plant pathogens Colletotrichum lindemuthianum, Fusarium oxysporum, and Sclerotium rolfsii. The inhibitor of the C. lindemuthianum polygalacturonase, purified 560-fold from bean hypocotyl extracts, is 40 times as effective an inhibitor of the C. lindemuthianum polygalacturonase as of the F. oxysporum polygalacturonase, and does not demonstrably inhibit the S. rolfsii polygalacturonase. A crude hypocotyl extract that completely inhibits the three polygalacturonases does not inhibit C. lindemuthianum-secreted cellulase, xylanase, alpha-galactosidase, alpha-arabinofuranosidase, or alpha-galacturonosidase. The purified bean hypocotyl protein combines with the C. lindemuthianum polygalacturonase to form a complex with a dissociation constant of 2 x 10(-9) M or less. The physical properties of these inhibitors are similar to those of phytohemagglutinins and of the plant glycoproteins capable of agglutinating transformed animal cells.

Unexplained syncope evaluated by electrophysiologic studies and head-up tilt testing

OBJECTIVE

To determine the clinical characteristics of subgroups of patients with unexplained syncope having electrophysiologic studies and head-up tilt testing and to assess the efficacy of various therapies.

DESIGN

Retrospective study.

SETTING

Inpatient services of a tertiary referral center.

PATIENTS

Eighty-six consecutively referred patients with unexplained syncope.

MEASUREMENTS

All patients had electrophysiologic examinations. Patients with negative results subsequently had head-up tilt testing.

MAIN RESULTS

Twenty-nine (34%) patients (group 1) had abnormal electrophysiologic results, with sustained monomorphic ventricular tachycardia induced in 72%. Thirty-four (40%) patients (group 2) had syncope provoked by head-up tilt testing. The cause of syncope remained unexplained in 23 (26%) patients (group 3). Structural heart disease was present in 76%, 6%, and 30% of groups 1, 2, and 3, respectively. In group 1, pharmacologic or nonpharmacologic therapy was recommended based on electrophysiologic evaluation. All group 2 patients had negative results on head-up tilt testing while receiving oral beta blockers (27 patients) or disopyramide (7 patients). Group 3 patients did not receive any specific therapy. During a median follow-up period of 18.5 months, syncope recurred in 9 (10%) patients.

CONCLUSIONS

The combination of electrophysiologic evaluation and head-up tilt testing can identify the underlying cause of syncope in as many as 74% of patients presenting with unexplained syncope. Therapeutic strategies formulated according to the results of these diagnostic tests appear to prevent syncope effectively in most patients.

Human neural stem cells differentiate and promote locomotor recovery in an early chronic spinal cord injury NOD-scid mouse model

Background

Traumatic spinal cord injury (SCI) results in partial or complete paralysis and is characterized by a loss of neurons and oligodendrocytes, axonal injury, and demyelination/dysmyelination of spared axons. Approximately 1,250,000 individuals have chronic SCI in the U.S.; therefore treatment in the chronic stages is highly clinically relevant. Human neural stem cells (hCNS-SCns) were prospectively isolated based on fluorescence-activated cell sorting for a CD133⁺ and CD24^−/lo population from fetal brain, grown as neurospheres, and lineage restricted to generate neurons, oligodendrocytes and astrocytes. hCNS-SCns have recently been transplanted sub-acutely following spinal cord injury and found to promote improved locomotor recovery. We tested the ability of hCNS-SCns transplanted 30 days post SCI to survive, differentiate, migrate, and promote improved locomotor recovery.

Methods and Findings

hCNS-SCns were transplanted into immunodeficient NOD-scid mice 30 days post spinal cord contusion injury. hCNS-SCns transplanted mice demonstrated significantly improved locomotor recovery compared to vehicle controls using open field locomotor testing and CatWalk gait analysis. Transplanted hCNS-SCns exhibited long-term engraftment, migration, limited proliferation, and differentiation predominantly to oligodendrocytes and neurons. Astrocytic differentiation was rare and mice did not exhibit mechanical allodynia. Furthermore, differentiated hCNS-SCns integrated with the host as demonstrated by co-localization of human cytoplasm with discrete staining for the paranodal marker contactin-associated protein.

Conclusions

The results suggest that hCNS-SCns are capable of surviving, differentiating, and promoting improved locomotor recovery when transplanted into an early chronic injury microenvironment. These data suggest that hCNS-SCns transplantation has efficacy in an early chronic SCI setting and thus expands the “window of opportunity” for intervention.

Polymorphonuclear leukocytes promote neurotoxicity through release of matrix metalloproteinases, reactive oxygen species, and TNF-α

As the first immune cells to infiltrate the nervous system after traumatic PNS and CNS injury, neutrophils (polymorphonuclear leukocytes, PMNs) may promote injury by releasing toxic soluble factors that may affect neuronal survival. Direct neurotoxicity of matrix metalloproteinases (MMPs), reactive oxygen species (ROS), and cytokines released by PMNs was investigated by culturing dorsal root ganglion (DRG) cells with PMN-conditioned media containing MMP inhibitor (GM6001), ROS scavengers, or tumor necrosis factor alphaR (TNF-alphaR) neutralizing antibody. Although DRGs exposed to PMN-conditioned media had 53% fewer surviving neurons than controls, neuronal cell loss was prevented by GM6001 (20 micromol/L), catalase (1000 U/mL), or TNF-alphaR neutralizing antibody (1.5 microg/mL), elevating survival to 77%, 94%, and 95%, respectively. In accordance with protection by GM6001, conditioned media collected from MMP-9 null PMNs was less neurotoxic than that collected from wild-type PMNs. Additionally, MMP inhibition reduced PMN-derived ROS; removal of ROS reduced PMN-derived MMP-9 activity; and TNF-alpha inhibition reduced both PMN-derived MMP-9 activity and ROS in PMN cultures. Our data provide the first direct evidence that PMN-driven neurotoxicity is dependent on MMPs, ROS, and TNF-alpha, and that these factors may regulate PMN release of these soluble factors or interact with one another to mediate PMN-driven neurotoxicity.

Accumulation of a poly(hydroxyalkanoate) copolymer containing primarily 3-hydroxyvalerate from simple carbohydrate substrates by Rhodococcus sp. NCIMB 40126

A number of taxonomically-related bacteria have been identified which accumulate poly(hydroxyalkanoate) (PHA) copolymers containing primarily 3-hydroxyvalerate (3HV) monomer units from a range of unrelated single carbon sources. One of these, Rhodococcus sp. NCIMB 40126, was further investigated and shown to produce a copolymer containing 75 mol% 3HV and 25 mol% 3-hydroxybutyrate (3HB) from glucose as sole carbon source. Polyesters containing both 3HV and 3HB monomer units, together with 4-hydroxybutyrate (4HB), 5-hydroxyvalerate (5HV) or 3-hydroxyhexanoate (3HHx), were also produced by this organism from certain accumulation substrates. With valeric acid as substrate, almost pure (99 mol% 3HV) poly(3-hydroxyvalerate) was produced. N.m.r. analysis confirmed the composition of these polyesters. The thermal properties and molecular weight of the copolymer produced from glucose were comparable to those of PHB produced by Alcaligenes eutrophus.

Increased immunoreactivity for Jun- and Fos-related proteins in Alzheimer's disease: association with pathology

The protein products of the Jun and Fos immediate early gene (IEG) families are cooperative transcriptional regulatory factors implicated in regulating the expression of many genes. The levels of a variety of proteins such as the amyloid precursor protein and basic fibroblast growth factor are altered in Alzheimer's disease (AD), thus the events regulating these changes are of interest. Both of these genes contain an activator protein-1 consensus sequence which may be responsive to regulation by immediate early genes. In order to evaluate the potential involvement of IEGs in AD pathology, we have examined Jun- and Fos-related protein immunoreactivity in control and AD brain. Specifically, we investigated the correspondence of immunoreactivity for Jun and Fos proteins with immunoreactivity for paired helical filament-1 (PHF-1), a marker for neurofibrillary tangles which recognizes abnormally phosphorylated tau, glial fibrillary acidic protein (GFAP), and thioflavine staining in double-labeling experiments. An intensification of both Jun and Fos immunoreactivity was observed in AD cases; in addition, both Jun and Fos immunoreactivity were colocalized with PHF-1 in some neurons in AD brain. Jun and Fos immunoreactivity were also colocalized with GFAP-positive astrocytes distributed in the cortex of AD and control cases, and surrounding thioflavine-stained plaques in AD brain. These observations suggest that members of the Jun and Fos IEG families may play a role in AD pathology.

Echocardiographic demonstration of decreased left ventricular dimensions and vigorous myocardial contraction during syncope induced by head-up tilt

Two-dimensional echocardiography was performed during a head-up tilt test in 11 control subjects (group I) and 18 patients with recurrent unexplained syncope. In four patients (group II), the head-up tilt test was negative at baseline and after isoproterenol infusion. Syncope was induced during baseline head-up tilt in nine patients (group III) and after isoproterenol challenge in five (group IV). The echocardiographic variables assessed were left ventricular end-systolic and end-diastolic areas and percent fractional shortening. At the end of head-up tilt, end-systolic area decreased by 4.5 +/- 1.3 and 3.0 +/- 1.2 cm2 in groups III and IV, respectively, compared with 0.5 +/- 0.7 and 0.2 +/- 0.1 cm2 in groups I and II, respectively (p less than 0.04). Similarly, end-diastolic area decreased by 5.5 +/- 2.6 cm2 in group III compared with 2.7 +/- 1.9 and 1.75 +/- 0.4 cm2 in group I and II, respectively (p less than 0.04). Additionally, at the end of the baseline study, fractional shortening was significantly greater in group III and group IV (43 +/- 5%) than in groups I and II (p less than 0.01). In conclusion, syncope induced by head-up tilt is associated with vigorous myocardial contraction and a significant decrease in left ventricular end-systolic dimensions. This left ventricular hypercontractility may play an important role in the pathogenesis of syncope induced by head-up tilt.

Cloning and characterization of the katB gene of Pseudomonas aeruginosa encoding a hydrogen peroxide-inducible catalase: purification of KatB, cellular localization, and demonstration that it is essential for optimal resistance to hydrogen peroxide

Pseudomonas aeruginosa is an obligate aerobe that is virtually ubiquitous in the environment. During aerobic respiration, the metabolism of dioxygen can lead to the production of reactive oxygen intermediates, one of which includes hydrogen peroxide. To counteract the potentially toxic effects of this compound, P. aeruginosa possesses two heme-containing catalases which detoxify hydrogen peroxide. In this study, we have cloned katB, encoding one catalase gene of P. aeruginosa. The gene was cloned on a 5.4-kb EcoRI fragment and is composed of 1,539 bp, encoding 513 amino acids. The amino acid sequence of the P. aeruginosa katB was approximately 65% identical to that of a catalase from a related species, Pseudomonas syringae. The katB gene was mapped to the 71- to 75-min region of the P. aeruginosa chromosome, the identical region which harbors both sodA and sodB genes encoding both manganese and iron superoxide dismutases. When cloned into a catalase-deficient mutant of Escherichia coli (UM255), the recombinant P. aeruginosa KatB was expressed (229 U/mg) and afforded this strain resistance to hydrogen peroxide nearly equivalent to that of the wild-type E. coli strain (HB101). The KatB protein was purified to homogeneity and determined to be a tetramer of approximately 228 kDa, which was in good agreement with the predicted protein size derived from the translated katB gene. Interestingly, KatB was not produced during the normal P. aeruginosa growth cycle, and catalase activity was greater in nonmucoid than in mucoid, alginate-producing organisms. When exposed to hydrogen peroxide and, to a greater extent, paraquat, total catalase activity was elevated 7- to 16-fold, respectively. In addition, an increase in KatB activity caused a marked increase in resistance to hydrogen peroxide. KatB was localized to the cytoplasm, while KatA, the "housekeeping" enzyme, was detected in both cytoplasmic and periplasmic extracts. A P. aeruginosa katB mutant demonstrated 50% greater sensitivity to hydrogen peroxide than wild-type bacteria, suggesting that KatB is essential for optimal resistance of P. aeroginosa to exogenous hydrogen peroxide.

Accumulation of a Polyhydroxyalkanoate Containing Primarily 3-Hydroxydecanoate from Simple Carbohydrate Substrates by Pseudomonas sp. Strain NCIMB 40135

A number of Pseudomonas species have been identified which accumulate a polyhydroxyalkanoate containing mainly 3-hydroxydecanoate monomers from sodium gluconate as the sole carbon source. One of these, Pseudomonas sp. strain NCIMB 40135, was further investigated and shown to accumulate such a polyhydroxyalkanoate from a wide range of carbon sources (C(2) to C(6)); however, when supplied with octanoic acid it produced a polyhydroxyalkanoate containing mainly 3-hydroxyoctanoate monomers. Polymer synthesis occurred in batch culture after cessation of growth due to exhaustion of nitrogen. In continuous culture under nitrogen limitation up to 16.9% (wt/wt) polyhydroxyalkanoate was synthesized from glucose as the carbon source. The monomer units are mainly of the R-(-) configuration. Nuclear magnetic resonance studies confirmed the composition of the polymer. Differential scanning calorimetry suggested that the solvent-extracted polymer contained a significant proportion of crystalline material. The weight-average molecular weight of the polymer from glucose-grown cells was 143,000.

Correlation between caspase activation and neurofibrillary tangle formation in Alzheimer's disease

Although evidence suggests that neurofibrillary tangles (NFTs) and neuronal cell loss are prominent features of Alzheimer's disease (AD), the relationship between the two remains unknown. In the present study, the relationship between the activation of apoptotic mechanisms and NFT formation in AD was investigated using a caspase-cleavage site-directed antibody to fodrin, an abundant neuronal cytoskeleton protein. This antibody recognized cleavage products of fodrin after digestion by caspase-3, but did not recognize full-length fodrin. In vitro analysis of this fodrin caspase-cleavage product (CCP) antibody demonstrates that it is a specific probe for the detection of apoptotic but not necrotic pathways in cultured neurons. To determine whether caspases cleave fodrin in vivo, tissue sections from controls and AD were immunostained for fodrin (CCPs). Although no staining was observed in control cases, labeling of neurons was observed in the hippocampus of all AD cases, which increased as a function of disease progression. To determine a possible relationship between caspase activation and NFT formation, double-labeling experiments with fodrin CCP and PHF-1 were performed. Co-localization of these markers was observed in many neurons, and quantitative analysis showed that as the extent of NFT formation increased, there was a significant corresponding increase in fodrin CCP immunolabeling (r = 0.84). Taken together, these results provide evidence for the activation of apoptotic mechanisms in neurons in the AD brain and suggest that there is an association between NFT formation and the activation of apoptotic pathways in AD.

Body fat distribution and male/female differences in lipids and lipoproteins

The role of body fat distribution, as assessed by the ratio of waist-to-hip circumferences (WHR), in statistically explaining differences in levels of lipoproteins between men and women was studied using data collected in 1985-1986 from employed adults (mean age, 40 years). As compared with the 415 women, the 709 men had higher mean levels of triglycerides (+38 mg/dl) and apolipoprotein B (+11 mg/dl) as well as lower mean levels of high density lipoprotein (HDL) cholesterol (-15 mg/dl) and apolipoprotein A-I (-19 mg/dl). Additionally, men were more overweight, consumed more alcohol, and exercised more frequently than women but were less likely to smoke cigarettes. Controlling for these characteristics, however, did not alter the differences in lipoprotein levels between men and women. In contrast, adjustment for WHR (which was greater among men) reduced the sex differences in levels of apolipoprotein B (by 98%), triglycerides (by 94%), HDL cholesterol (by 33%), and apolipoprotein A-I (by 21%). Similar results were obtained using analysis of covariance, stratification, or matching; at comparable levels of WHR, differences in lipid and lipoprotein levels between men and women were greatly reduced. Although these results are based on cross-sectional analyses of employed adults and need to be replicated in other populations, the findings emphasize the relative importance of body fat distribution. Whereas generalized obesity and body fat distribution are associated with lipid levels, fat distribution (or a characteristic influencing fat patterning) can be an important determinant of sex differences in levels of triglycerides, HDL cholesterol, and apolipoproteins B and A-I.

Voluntary Wheel Running Improves Recovery from a Moderate Spinal Cord Injury

Recently, locomotor training has been shown to improve overground locomotion in patients with spinal cord injury (SCI). This has triggered renewed interest in the role of exercise in rehabilitation after SCI. However, there are no mouse models for voluntary exercise and recovery of function following SCI. Here, we report voluntary wheel running improves recovery from a SCI in mice. C57Bl/10 female mice received a 60-kdyne T9 contusion injury with an IH impactor after 3 weeks of voluntary wheel running or 3 weeks of standard single housing conditions. Following a 7-day recovery period, running mice were returned to their running wheels. Weekly open-field behavior measured locomotor recovery using the Basso, Beattie and Bresnahan (BBB) locomotor rating scale and the Basso Mouse Scale (BMS) locomotor rating scale, a scale recently developed specifically for mice. Initial experiments using standard rung wheels show that wheel running impaired recovery, but subsequent experiments using a modified flat-surface wheel show improved recovery with exercise. By 14 days post SCI, the modified flat-surface running group had significantly higher BBB and BMS scores than the sedentary group. A repeated measures ANOVA shows locomotor recovery of modified flat-surface running mice was significantly improved compared to sedentary animals (p < 0.05). Locomotor assessment using a ladder beam task also shows a significant improvement in the modified flat-surface runners (p < 0.05). Finally, fibronectin staining shows no significant difference in lesion size between the two groups. These data represent the first mouse model showing voluntary exercise improves recovery after SCI.